This invention relates to apparatus for measuring nuclear radiation which includes a probe comprising a synthetic diamond.
Diamonds have been found to have several advantages when used as detectors of nuclear radiation. These advantages include their small physical size and their ability to work over a wide temperature range. Diamonds are also tissue equivalent, which makes their use in the medical field attractive. Diamonds may be used in a conduction mode for high levels of radiation, or in a pulse counting mode for both high and low levels of radiation.
Due to the extremely high impedance of diamonds, an amplifier having a very high input impedance is required to amplify pulses or a conduction signal from the diamond. This generally requires the use of field-effect transistors (FETS). For use in the conduction mode, the amplifier must have very low DC drift. The amplifier should not saturate at high DC input levels, when the diamond is exposed to high dose rates in the conduction mode. The amplifier should further be capable of coping with pulses having a fast rise time in the pulse counting mode.